It is known in modern automobile manufacture to employ laminated metal, particularly laminated steel, in the forming of components such as oil pans, rocker covers, wheelhouse inners and front-dash structures. Laminated metal is comprised of two sheets of metal, such as steel, aluminum or magnesium, with a layer of polymer interposed there between. Laminated metal is known to provide a good combination of vibration damping properties and high strength-to-weight ratios and is accordingly of interest to the exacting performance demands of the automobile industry.
It is known to weld fasteners and other components to the laminated metal by conventional welding processes such as projection resistance welding. However, in such processes, the fastener is welded to only the outer layer of metal of the laminated metal, rather than to both layers of metal. In addition, the use of electric resistance welding is complicated by the fact that the layer of polymer acts as a dielectric to retard to flow of welding current through the laminated metal.